The derlin plastic can be any color, the plastic epoxy I got is white. Most places dont have derlin, it's expensive & strong enough to make gears out of. Most plastic in stores is that cutting board stuff, its hdpe or uhmw plastic.
Yes it could, thats also probably why your high end race cranks are stuffed. To restore your crankcase pressure or whatever its called & to help reduce turbulence
The total thickness and weight is not really an issue because you are balancing rotating mass vs the reciprocating mass and want it to statically balance, as long as you didn't nick the rod your fine!